ABSTRACT:

Objective:

To estimate the coverage of the first and second dose of the human papillomavirus (HPV) vaccine in Brazil according to microregion, comparing cohorts of girls aged 14, 15, and 16 years in 2017, and investigate the association between spatial heterogeneity in vaccination coverage and sociodemographic variables.

Methods:

Information about the doses administered from 2013 to 2017 by age was gathered from the National Immunization Program. The number of girls aged seven, eight, and nine years living in each microregion in 2010 was obtained from the 2010 Brazilian Census. For the analysis, the cumulated vaccination coverage per microregion (n = 558) was categorized as low (< 80%) and adequate (≥ 80%), and a random intercept logistic model was adjusted, with adequate vaccination coverage as the outcome. The random effect (federative unit) was included to identify the correlation between microregions that belong to the same state.

Results:

The percentage of microregions with adequate vaccination coverage was significantly higher in the first dose (between 91.8 and 159.2%), regardless of the cohort. The coverage of the second dose was lower (between 7 and 79.9%), with heterogeneity associated with the degree of urbanization and households with private bathrooms in the municipality. The random effect showed a strong explanatory power, suggesting important differences among Brazilian states as to the outreach of vaccination coverage.

Conclusion:

Although the HPV vaccine is available through the Immunization Program, the findings of the present study point to a difficulty in achieving adequate vaccination coverage.

Keywords:
Immunization; Vaccination coverage; Papillomaviridae; Ecological studies

INTRODUCTION

The human papillomavirus (HPV) is one of the most common sexually transmitted infections in the world. Estimates indicate that, in 2015, 291 million women were carriers of the virus worldwide¹1. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de DST, Aids e Hepatites Virais. Protocolo Clínico e Diretrizes Terapêuticas para Atenção Integral às Pessoas com Infecções Sexualmente Transmissíveis. Brasília: Ministério da Saúde; 2015. 120 p.^,22. Sanjosé S, Diaz M, Castellsagué X, Clifford G, Bruni L, Muñoz N, et al. Worldwide prevalence and genotype distribution of cervical human papillomavirus DNA in women with normal cytology: a meta-analysis. Lancet Infect Dis 2007; 7(7): 453-9. https://doi.org/10.1016/S1473-3099(07)70158-5
https://doi.org/https://doi.org/10.1016/... . The persistence of some types of HPV infection can progress to cervical cancer, a disease that has 530 thousand new cases per year¹1. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de DST, Aids e Hepatites Virais. Protocolo Clínico e Diretrizes Terapêuticas para Atenção Integral às Pessoas com Infecções Sexualmente Transmissíveis. Brasília: Ministério da Saúde; 2015. 120 p.^,33. Instituto Nacional de Câncer José Alencar Gomes da Silva. Estimativa 2020: incidência de câncer no Brasil. Rio de Janeiro: INCA; 2019. 120 p.. One of the main strategies for controlling this type of cancer is vaccination.

In the Americas, the HPV vaccine was introduced in 2006 in the United States, and, by mid-2019, it was present in the schedules of 40 countries and territories⁴4. Organização Pan-Americana da Saúde. Metodologia para o cálculo de cobertura da vacina contra o HPV na Região das Américas. Washington, D.C.: OPAS; 2019. 18 p.. The quadrivalent vaccine has been the most used in 2020. It protects against infections caused by HPV types 6, 11, 16, and 18 and is recommended for girls and women aged 9 to 45 years and boys and men aged 9 to 26 years⁵5. Merck Sharp & Dohme Farmacêutica Ltda. Gardasil. Vacina papilomavírus humano 6, 11, 16 e 18 (recombinante). Merck Sharp & Dohme Farmacêutica Ltda..

In Brazil, the quadrivalent HPV vaccine was incorporated into the National Immunization Program (NIP) for free in 2014⁶6. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Vigilância das Doenças Transmissíveis. Coordenação-Geral do Programa Nacional de Imunizações. Informe técnico sobre a vacina papilomavírus humano (HPV) na atenção básica [Internet]. 2014 [acessado em 20 jan. 2019]. Disponível em: Disponível em: https://portalarquivos2.saude.gov.br/images/pdf/2015/junho/26/Informe-T--cnico-Introdu----o-vacina-HPV-18-2-2014.pdf
https://portalarquivos2.saude.gov.br/ima... . The inclusion of target populations in the vaccination schedule was gradual. It consisted of girls aged 11 to 13 years in 2014, was extended to the age group of 9 to 11 years in 2015, and to girls aged 14 years in 2017. This year, the program targeted girls aged 9 to 14 years and boys aged 11 to 14 years⁷7. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Vigilância das Doenças Transmissíveis. Coordenação-Geral do Programa Nacional de Imunizações. Informe técnico da ampliação da oferta das vacinas papilomavírus humano 6, 11, 16 e 18 (recombinante) - vacina HPV quadrivalente e meningocócica C (conjugada) [Internet]. 2018 [acessado em 15 jan. 2019]. Disponível em: Disponível em: https://portalarquivos2.saude.gov.br/images/pdf/2018/marco/14/Informe-T--cnico-HPV-MENINGITE.pdf
https://portalarquivos2.saude.gov.br/ima... .

The objective of the NIP is to achieve at least 80% of vaccination coverage in the first and second doses⁷7. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Vigilância das Doenças Transmissíveis. Coordenação-Geral do Programa Nacional de Imunizações. Informe técnico da ampliação da oferta das vacinas papilomavírus humano 6, 11, 16 e 18 (recombinante) - vacina HPV quadrivalente e meningocócica C (conjugada) [Internet]. 2018 [acessado em 15 jan. 2019]. Disponível em: Disponível em: https://portalarquivos2.saude.gov.br/images/pdf/2018/marco/14/Informe-T--cnico-HPV-MENINGITE.pdf
https://portalarquivos2.saude.gov.br/ima... . In 2014, 87% of Brazilian municipalities reached the recommended target for the first dose, but only 32% reached the recommended target for the second dose. The explanations listed for the low coverage were the difficulty of access, failures in recording the doses of vaccines administered, typing errors, and inaccuracies in the demographic data used to estimate the number of individuals in the target age group⁸8. Moro A, Santos CL, Couto MP, Ávila LB, Ditterich RG, Mazon LM. Coberturas vacinais do Papiloma Vírus Humano no contexto brasileiro. Saúde Meio Ambiente [Internet] 2017 [acessado em 15 fev. 2019]; 6(2): 124-32. Disponível em: Disponível em: http://www.periodicos.unc.br/index.php/sma/article/view/1528 https://doi.org/10.24302/sma.v6i2.1528
http://www.periodicos.unc.br/index.php/s... ^,99. Tobias GC, Iwamoto KOFI, Teixeira LMB. Estratégia de vacinação contra HPV. Rev Enferm UFPE On Line 2017; 11(12): 5282-8. https://doi.org/10.5205/1981-8963-v11i12a22841p5282-5288-2017
https://doi.org/https://doi.org/10.5205/... .

At the individual level, several factors have been analyzed and reported as associated with low HPV vaccination coverage, especially low schooling, low income, living in a rural area, low access to information and health services, and barriers imposed by religious dogmas¹⁰10. Fernández-Feito A, Lana A, Parás Bravo P, Pellico López A, Paz-Zulueta M. Knowledge of the Human Papillomavirus by Social Stratification Factors. Nurs Res 2020; 69(3): E18-25. https://doi.org/10.1097/NNR.0000000000000413
https://doi.org/https://doi.org/10.1097/... ^,1111. Thompson EL, Rosen BL, Maness SB. Social Determinants of Health and Human Papillomavirus Vaccination Among Young Adults, National Health Interview Survey. J Community Health 2019; 44(1): 149-58. https://doi.org/10.1007/s10900-018-0565-2
https://doi.org/https://doi.org/10.1007/... ^,1212. Kruse MH, Bednarczyk RA, Evans DP. A human rights approach to understanding provider knowledge and attitudes toward the human papillomavirus vaccine in São Paulo, Brazil. Papillomavirus Res 2020; 9: 100197. https://doi.org/10.1016/j.pvr.2020.100197
https://doi.org/https://doi.org/10.1016/... ^,1313. Tiley K, White J, Andrews N, Tessier E, Ramsay M, Edelstein M. What school-level and area-level factors influenced HPV and MenACWY vaccine coverage in England in 2016/2017? An ecological study. BMJ Open 2019; 9(7): e029087. https://doi.org/10.1136/bmjopen-2019-029087
https://doi.org/https://doi.org/10.1136/... ^,1414. World Health Organization. Guide to Introducing HPV Vaccine into National Immunization Programmes. Genebra: World Health Organization; 2017. 91 p.. Meanwhile, population analyses, with aggregated data, contribute to understanding social or structural determinants connected to the vaccination coverage achieved in a geographic area. For instance, household conditions (such as having a private bathroom) and access to public services (such as waste collection and running water) are proxies of the socioeconomic status of a location. Thus, we can infer that the higher the socioeconomic status of the municipality, the more likely it is to reach the recommended vaccination coverage. Similarly, more urban municipalities have a higher chance of achieving the desired coverage because they have broader dissemination of information on vaccination campaigns and offer health services with a supply of vaccines.

The present study aimed at analyzing the estimates of HPV vaccination coverage in Brazil in 2017, comparing cohorts of girls aged 14, 15, and 16 years in that year. We also sought to identify geographic heterogeneities in the coverage and test the association of municipal indicators with the vaccination coverage.

METHODS

We calculated the HPV vaccination coverage in three age cohorts of girls living in Brazil in 2017, stratified by microregions (n = 558 microregions). The cohorts were selected according to the start of vaccine availability. Thus, cohort 1 consisted of girls aged 10 years in 2013 who turned 14 in 2017; cohort 2 included girls aged 11 years in 2013 who turned 15 in 2017; and cohort 3 comprised girls aged 12 years in 2013 who turned 16 in 2017. Each of these cohorts had different opportunities to be vaccinated according to schedule changes.

DATA

Vaccination data were collected from the Immunization Program Evaluation System (Sistema de Avaliação do Programa de Imunizações - API), which is administered by the National Immunization Program General Coordination (Coordenação Geral do Programa Nacional de Imunizações - CGPNI) of the Ministry of Health¹⁵15. Brasil. Ministério da Saúde. Informações de Saúde. DATASUS, Imunizações-Doses aplicadas - Brasil [Internet]. 2019.[acessado em 4 abr. 2019]. Disponível em: Disponível em: http://tabnet.datasus.gov.br/cgi/tabcgi.exe?pni/cnv/DPniuf.def
http://tabnet.datasus.gov.br/cgi/tabcgi.... . We obtained the numbers of doses administered by age from 2013 to 2017, considering the first and second doses separately. The number of girls aged seven, eight, and nine years living in each microregion in 2010 was gathered from the 2010 Demographic Census. These girls comprised the target population of the three vaccination cohorts that started in 2013. We used the definition and spatial profile of microregions established by the Brazilian Institute of Geography and Statistics (Instituto Brasileiro de Geografia e Estatística - IBGE)¹⁶16. Instituto Brasileiro de Geografia e Estatística. Censo 2010 [Internet]. IBGE; 2010 [acessado em 10 jul. 2019]. Disponível em: Disponível em: https://censo2010.ibge.gov.br/
https://censo2010.ibge.gov.br/... .

The following variables were used to investigate whether the spatial heterogeneity of the vaccination coverage was associated with the sociodemographic characteristics of the microregions: proportion of the urban population; proportion of households with waste collection; proportion of households with access to running water; proportion of households with private bathroom; proportion of the population with private health insurance; and proportion of the population with income lower than one minimum wage. These data were calculated based on the 2010 IBGE census records. The random variable federative unit (categorical) was included to identify the structure of dependence between microregions that belong to the same state since they share public policies. Confidence intervals of random effects were obtained assuming a normal distribution. Maps were constructed with shapefiles provided by IBGE.

VACCINATION COVERAGE

We calculated the vaccination coverage using the method of cumulated coverage per cohort recommended by the NIP⁷7. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Vigilância das Doenças Transmissíveis. Coordenação-Geral do Programa Nacional de Imunizações. Informe técnico da ampliação da oferta das vacinas papilomavírus humano 6, 11, 16 e 18 (recombinante) - vacina HPV quadrivalente e meningocócica C (conjugada) [Internet]. 2018 [acessado em 15 jan. 2019]. Disponível em: Disponível em: https://portalarquivos2.saude.gov.br/images/pdf/2018/marco/14/Informe-T--cnico-HPV-MENINGITE.pdf
https://portalarquivos2.saude.gov.br/ima... . This methodology consists in identifying age cohorts, defined as the set of girls who turned the same age in the same calendar year. The numerator was the cumulative sum of vaccine doses administered to each cohort since the first year they became eligible. The denominator was the number of girls aged seven, eight, and nine years residing in each Brazilian microregion in 2010. The present study defined three cohorts: girls aged 14 years in 2017 who were eligible for vaccination from 2014-2017 (aged 11, 12, 13, and 14 years), girls aged 15 years in 2017 who were eligible for vaccination from 2013-2015 (aged 11, 12, and 13 years), and girls aged 16 years in 2017 who were eligible for vaccination from 2013-2014 (aged 12 and 13 years) (Chart 1).

ANALYSIS

The cumulated vaccination coverage per microregion was categorized as low (< 80%) and adequate (≥ 80%), following the classification established by the NIP⁶6. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Vigilância das Doenças Transmissíveis. Coordenação-Geral do Programa Nacional de Imunizações. Informe técnico sobre a vacina papilomavírus humano (HPV) na atenção básica [Internet]. 2014 [acessado em 20 jan. 2019]. Disponível em: Disponível em: https://portalarquivos2.saude.gov.br/images/pdf/2015/junho/26/Informe-T--cnico-Introdu----o-vacina-HPV-18-2-2014.pdf
https://portalarquivos2.saude.gov.br/ima... , and calculated separately for the first and second doses. A random intercept logistic model was adjusted, with adequate vaccination coverage as the outcome¹⁷17. Gałecki AT, Burzykowski T. Linear mixed-effects models using R: a step-by-step approach. Nova York: Springer; 2013. 542 p.. The fixed effect explanatory variables were: proportion of urban population, proportion of households with waste collection, access to running water, private bathroom, and income lower than one minimum wage. The models were adjusted using the lme4 library of the R environment, version 3.4.4¹⁶16. Instituto Brasileiro de Geografia e Estatística. Censo 2010 [Internet]. IBGE; 2010 [acessado em 10 jul. 2019]. Disponível em: Disponível em: https://censo2010.ibge.gov.br/
https://censo2010.ibge.gov.br/... , and the results were displayed with the sjPlot library. Maps were constructed using the maptools library.

The secondary data used in the present study are anonymized and of public domain; thus, the research did not need to be submitted to and approved by a Research Ethics Committee.

RESULTS

The percentage of microregions with adequate vaccination coverage was significantly higher in the first dose, regardless of the cohort (cohort 1: 98%, cohort 2: 95%, cohort 3: 92.5%). However, a concentration of microregions with low coverage was identified in Northern Brazil, particularly in Amazonas (Table 1 and Figure 1) and some areas of Pará. We underline that the Federal District also presented inadequate coverage in the first dose (Table 1). The second dose showed lower coverage in general, reaching only 37% in cohort 1, 61% in cohort 2, and 37% in cohort 3. The distribution of vaccination coverage was spatially heterogeneous, as seen in Figure 1.

The logistic model best adjusted for the coverage of the first dose had only the cohorts as a significant fixed effect. For this dose, the youngest cohort was more likely to achieve the goal than the older cohorts 2 and 3 (cohort 2: odds ratio - OR = 0.09, confidence interval - 95%CI 0.02 - 0.35; cohort 3: 0.04, 95%CI 0.01 - 0.17). As for the second dose, the cohort effect was reversed, with cohort 2 having a greater chance of being vaccinated (cohort 2: OR = 4.48, 95%CI 3.3 - 6.09). In addition to the cohort effect, the percentage of urban population and of households with private bathroom showed a significant effect in the coverage of the second dose. Microregions with a higher urban population had a lower chance of achieving adequate coverage, but the effect was small (OR = 0.98, 95%CI 0.96 - 0.99).

Figure 2 shows the random effects estimated for each state. Values above 1 indicated greater “relative ease” to achieve adequate coverage, while lower values pointed to greater “relative difficulty”. Regarding the first dose, Amazonas (AM) had the highest random effect, with a large difference compared to other states. As to the second dose, the differences between states were smaller. Nevertheless, some states, such as Pará (PA), Tocantins (TO), Piauí (PI), Paraíba (PB), Bahia (BA), Goiás (GO), and Paraná (PR), showed relatively greater difficulties in reaching the coverage in comparison with others, such as Maranhão (MA), Ceará (EC), Espírito Santo (ES), and Roraima (RR). The variable federative unit represented an important source of variation between the coverages reached, both in the first (variance = 5) and second (variance = 2.54) doses.

DISCUSSION

The first dose had the highest percentage of microregions with adequate vaccination coverage, regardless of the cohort, compared to the second dose. The logistic model revealed that cohort 1 was more likely to reach the goal in the first dose, while for the second dose, cohort 2 had a greater chance of reaching the goal.

In Brazil, although the NIP stands out for its successful experiences in Brazilian public health, it is challenged by the complexity of the national epidemiological context, the sociodemographic indicators, and the inclusion of new vaccines in the schedule¹⁷17. Gałecki AT, Burzykowski T. Linear mixed-effects models using R: a step-by-step approach. Nova York: Springer; 2013. 542 p.^,1818. Silva Junior JB. 40 anos do Programa Nacional de Imunizações: uma conquista da Saúde Pública brasileira. Epidemiol Serv Saúde [Internet] 2013 [acessado em 20 fev. 2019]; 22(1): 7-8. Disponível em: Disponível em: http://scielo.iec.gov.br/scielo.php?script=sci_arttext&pid=S1679-49742013000100001 http://dx.doi.org/10.5123/S1679-49742013000100001
http://scielo.iec.gov.br/scielo.php?scri... . The inclusion of the HPV vaccine for a target population different from that of routinely vaccinated children became a great challenge, and, to face it, several countries have created strategies for implementing vaccination in schools¹⁹19. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Vigilância das Doenças Transmissíveis. Manual de Normas e Procedimentos para Vacinação. Brasília: Ministério da Saúde ; 2014. 176 p.. Vaccination in Brazil was freely provided in schools, which are important learning places²⁰20. World Health Organization. Guidance note: comprehensive cervical cancer prevention and control: a healthier future for girls and women. Genebra: World Health Organization ; 2013. 12 p., and in basic health units, contributing to the vaccination coverage outreach in 2014.

The HPV vaccine has faced challenges, such as changes in the target population and vaccination regimen, over time²¹21. Siu JY, Lee A, Chan PKS. Schoolteachers’ experiences of implementing school-based vaccination programs against human papillomavirus in a Chinese community: a qualitative study. BMC Public Health 2019; 19(1): 1514. https://doi.org/10.1186/s12889-019-7878-7
https://doi.org/https://doi.org/10.1186/... . Despite the regional heterogeneity and specificities, the country had great success in the vaccination coverage of the first dose. This success is identified in the cohort of girls aged 14 years in 2017. This cohort had a higher chance of receiving the first dose of the vaccine, considering the inclusion of the HPV vaccine in the schedule and the gradual incorporation of the target population (of different ages along the years). National data indicate that cohorts of girls aged 13 and 14 years from 2013 to 2016 had a vaccination coverage above the recommended target (132.6 and 121.3%) in the first dose. Concerning the second dose, the vaccination coverage was below the recommended target in the cohort of girls aged 13 years (69%) and above the recommended goal (89.7%) in the cohort of girls aged 14 years²²22. Aps LRMM, Piantola MAF, Pereira SA, Castro JT, Santos FAO, Ferreira LCS. Adverse events of vaccines and the consequences of non-vaccination: a critical review. Rev Saúde Pública 2018; 52(40): 1-13. https://doi.org/10.11606/S1518-8787.2018052000384
https://doi.org/https://doi.org/10.11606... . The results of the present study regarding the vaccination coverage of cohorts 1 and 2 per microregions corroborate the Brazilian data for the first dose but disagree with those related to the second dose.

Comparing the cohorts, the coverage achieved in the first dose indicated a greater chance of younger cohorts being vaccinated, which possibly suggests an improvement in the vaccination program over the years. However, in the second dose, older cohorts were more likely to achieve the goal, which possibly points to a worsening of the program in maintaining high coverage for the second dose.

When we assessed the chances of a state achieving vaccination coverage after controlling for variations among cohorts, Amazonas stood out, as it had “relative difficulty” in reaching the coverage despite being the first state of the Northern region to offer the HPV vaccine in the public health system (Sistema Único de Saúde - SUS).

The analysis presented herein suggests an association between success in vaccination coverage and the proportion of households with bathrooms. This indicator measures both the situation of more than one household sharing a bathroom (more common in poorer urban households) and the use of septic tanks (more common in rural areas). In this context, microregions with higher values for this indicator can represent either more rural areas or poorer urban areas. This information corroborates findings of national adolescent immunization surveys, which identified that the coverage of the first dose of the HPV vaccine was significantly lower among adolescents from suburban and, particularly, rural areas than among those living in mostly urban areas²³23. Brasil. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Vigilância das Doenças Transmissíveis. Coordenação-Geral do Programa Nacional de Imunizações. Programa Nacional de Imunizações. Boletim Informativo. Vacinação contra HPV [Internet]. Brasil: Ministério da Saúde; 2016 [acessado em 4 ago. 2019]. Disponível em: http://portalarquivos2.saude.gov.br/images/pdf/2017/julho/28/Boletim-informativo.pdf.

Vaccination coverage also showed great heterogeneity between states, a finding not explained by the variables of urbanity and income used in the present study. These heterogeneities might be associated with different state public policies that affect the availability of vaccines for the population.

The present study highlights several challenges respecting the HPV vaccination coverage in Brazil. The estimated vaccination coverage of the first dose of the HPV vaccine in Brazil suggests high outreach, despite some locations not following the pattern (Federal District and Amazonas). In contrast, the second dose showed low cumulated vaccination coverage in all cohorts, with cohort 1 having the worst performance. This result implies that, despite the greater opportunity to receive the first dose, vaccination might be disrupted, a situation also called delayed vaccination. Delayed vaccination is recognized by the NIP as a recurring factor in other vaccines, hindering the protection against vaccine-preventable diseases in the population²⁴24. Williams CL, Walker TY, Elam-Evans LD, Yankey D, Fredua B, Saraiya M, et al. Factors associated with not receiving HPV vaccine among adolescents by metropolitan statistical area status, United States, National Immunization Survey-Teen, 2016-2017. Hum Vaccines Immunother 2020; 16(3): 562-72. https://doi.org/10.1080/21645515.2019.1670036
https://doi.org/https://doi.org/10.1080/... .

The reduction in vaccination coverage and, consequently, the resurgence of some diseases that had been eradicated in Brazil are worrying²⁵25. Tertuliano GC, Stein AT. Atraso vacinal e seus determinantes: um estudo em localidade atendida pela Estratégia Saúde da Família. Ciên Saúde Coletiva 2011; 16(2): 523-30. https://doi.org/10.1590/S1413-81232011000200015
https://doi.org/https://doi.org/10.1590/... . The drop in vaccination coverage might be related to the hesitancy toward vaccination, defined as the delayed acceptance or refusal of the vaccines recommended, despite their availability in health services²⁶26. Arroyo LH, Ramos ACV, Yamamura M, Weiller TH, Crispim J de A, Cartagena-Ramos D, et al. Áreas com queda da cobertura vacinal para BCG, poliomielite e tríplice viral no Brasil (2006-2016): mapas da heterogeneidade regional. Cad Saúde Pública 2020; 36(4): e00015619. https://doi.org/10.1590/0102-311x00015619
https://doi.org/https://doi.org/10.1590/... ^,2727. Cardin VSG, Nery LMG. Hesitação vacinal: direito constitucional à autonomia individual ou um atentado à proteção coletiva? Prisma Jur 2019; 18(2): 224-40. https://doi.org/10.5585/prismaj.v18n2.14482
https://doi.org/https://doi.org/10.5585/... . A study showed that the main reasons for the hesitancy toward vaccination are the lack of trust in the efficacy/safety of the vaccine and concerns with adverse events²⁸28. Sato APS. What is the importance of vaccine hesitancy in the drop of vaccination coverage in Brazil? Rev Saúde Pública 2018; 52: 96. https://doi.org/10.11606/S1518-8787.2018052001199
https://doi.org/https://doi.org/10.11606... .

Social media has an important role in spreading information and is one way to disseminate health recommendations. Nonetheless, we stress that the lack of information and/or fake information about the HPV vaccine can increase the issues related to adherence to vaccination²¹21. Siu JY, Lee A, Chan PKS. Schoolteachers’ experiences of implementing school-based vaccination programs against human papillomavirus in a Chinese community: a qualitative study. BMC Public Health 2019; 19(1): 1514. https://doi.org/10.1186/s12889-019-7878-7
https://doi.org/https://doi.org/10.1186/... ^,2929. Brown AL, Sperandio M, Turssi CP, Leite RMA, Berton VF, Succi RM, et al. Vaccine confidence and hesitancy in Brazil. Cad Saúde Pública 2018; 34(9): e00011618. https://doi.org/10.1590/0102-311x00011618
https://doi.org/https://doi.org/10.1590/... ^,3030. Sousa PDL, Takiuti AD, Baracat EC, Sorpreso ICE, Abreu LC de. Knowledge and acceptance of HPV vaccine among adolescents, parents and health professionals: construct development for collection and database composition. J Hum Growth Dev 2018; 28(1): 58-68. https://doi.org/10.7322/jhgd.143856
https://doi.org/https://doi.org/10.7322/... ^,3131. Icardi G, Costantino C, Guido M, Zizza A, Restivo V, Amicizia D, et al. Burden and Prevention of HPV. Knowledge, Practices and Attitude Assessment Among Pre-Adolescents and their Parents in Italy. Curr Pharm Des 2020; 26(3): 326-42. https://10.2174/1381612826666200114100553
https://doi.org/https://10.2174/13816128... ^,3232. Teoh D. The Power of Social Media for HPV Vaccination-Not Fake News! American Society of Clinical Oncology Educational Book 2019; (39): 75-8. https://doi.org/10.1200/EDBK_239363
https://doi.org/https://doi.org/10.1200/... .

The vaccination coverage of the second dose showed spatial heterogeneity. The variables associated with this coverage were: urban population and percentage of households with private bathrooms. This result suggests that variables related to social inequality, such as the percentage of households with private bathroom, influence the vaccination coverage, indicating that regions with better living conditions have a greater capacity to achieve coverage above the recommended target, perhaps by their greater access to health care³³33. Pereira da Veiga CR, Semprebon E, da Silva JL, Lins Ferreira V, Pereira da Veiga C. Facebook HPV vaccine campaign: insights from Brazil. Hum Vaccines Immunother 2020; 16(8): 1824-34. https://doi.org/10.1080/21645515.2019.1698244
https://doi.org/https://doi.org/10.1080/... .

The limitations of this study mainly involve inaccuracies in the calculation of vaccination coverage, which stem from uncertainties in the estimates of numerators and denominators. The numerator (number of doses administered) might not have properly measured the number of people vaccinated due to vaccine losses (vaccine wastage). Another bias could be the misclassification of first or second doses in information systems. On the other hand, the study advances when it compares the cumulated vaccination coverage in multiple cohorts and per microregion of the country. The results point to a successful vaccination coverage in the first dose and the need for greater attention to the second dose.

Although the HPV vaccine is available through the NIP, the findings of this research indicate the difficulty in maintaining the coverage outreach for the second dose, as well as the role of social inequality, which contributes to the spatial heterogeneity of vaccination coverage. This result shows the need for state managers to plan specific strategies for each area.

References

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